Hydraulic Cylinders which have been in storage for some time should be lubricated and cycled several times before they are installed on machines and subjected to actual working loads. Excessive break-loose and cycling pressures indicate the cylinder may have been damaged during shipment or storage. Costly installation and removal time can be eliminated by following this procedure. hydraulic cylinder should be stored In a vertical position with the piston rod up.
(1) :- An air or hydraulic cylinder is a precision piece of equipment, and therefore, it is recommended that tho cylinder be removed from the machine and taken to a general repair area where suitable tools, repair and testing facilities are available. (2) :- Dirt protector plugs should be kept in cylinder ports whenever the pipe fittings are remove doe while hydraulic cylinder storage. This prevents dirt and other foreign material from entering the hydraulic cylinder and damaging moving parts. (3) :- Be certain that the connecting pips and fittings are clean before connecting to the cylinder. All pipe ends should be debarred and the inside of the pipe cleaned of scale, rust, dirt and foreign matter.
(4) :- Clean oil is essential for long and satisfactory operation of hydraulic cylinder, pumps, valves etc. Keep oil tanks covered as even normal room dust causes premature failure sticking of parts, and needless repairs to hydraulic systems. Provide an adequate oil filter, preferably a micro filter. (5) :- For air cylinder (to operate furnace selector switch), provide a lubricator and filter in the air line, and use a light mineral oil as a lubricant. Use a pressure regulator to conserve air and to provide a smoother action. Save air and obtain greater speed by installing the valve as close to the cylinder port as possible.
Caution :- When cylinder require servicing, an additional set of seals should be ordered. The original seals may become damaged in servicing, and this precaution will save time and eliminate costly delays. Generally it is best to replace all seals unless the existing seals are in excellent condition or this is not economical or possible due to availability.
(6) :- Any seal can be damaged if forced over threads or sharp metal parts. All burrs and aged areas should be corrected prior to removing piston rod bushing and rod seal.
(7) :- Accordingly, care in assembly should be exercised. In the case of a rod seal, a simple shie ld of thin wrapping paper around the threads will permit easy installation of the seals without damage.
To remove a dirt wiper without taking the rod bushing off necessary to use a pointed tool as the wiper is lodged firmly. It may be necessary that the piston rod will not be damaged on removal of the wiper. A new wiper will not be damag Whenever the dirt wiper has a tendency to be blown out, it is an indication that the rod seal is leaking. Maintenance instruction of Air/hydraulic cylinder The following step-by-step outline will be a valuable aid to personnel qualified to service precision equipment. By exercising only normal care, which any good workman would accord fine machinery, no undue difficulty will be encountered
(1) :- Wipe all external surfaces clean :-
Drain excess oil from hydraulic cylinders. Painter draw a line on one side of the hydraulic cylinder running from the cylinder cap to the mounting end of the piston rod. This will serve as are furnace line when inspecting components and reassembling the cylinder
(2) :-VISUAL INSPECTION :- Visually inspect all external surfaces for evidence ot damage and in particular, damage to the piston rod. Evidence of rod seal leakage can usually be traced to nicks in the piston rod or misalignment. If a slight nick is noticed in the piston rod it can often be quickly removed by using a No.400 grit emery cloth. The rod should then be wiped carefully for removal of any matter.
UNDER NO CIRCUMSTANCES SHOULD COMPRESSED AIR BE USED TO REMOVE FOREIGN MATTER, as this practice may tend to drive such particles into close clearances. Misalignment can often be detected by observing the condition of the piston rods for evidence of excessive wear polishing, burnishing or scoring on the side of the piston rod. Check carefully the end of the piston rod and the area around the flats on the end of the rod for burrs and nicks.
If burrs and nicks are present, remove with a file or emery cloth to avoid damage to the piston rod seal, rod wiper, and bushing during removal.
(3) :- LOOSENING THE TIE RODS:- Proceed to loosen the four cylinder tie rods, noting if the tie rods were tightened evenly It may be necessary, in some cases, to grip the tie rod with vise grips to prevent the tie rod from tuning.
(4) :- REMOVAL OF RETAINER PLATE:- Remove retainer plate, (in some cases, this may be a flange mounting plate) Model ‘A,8 through 14 bores have a square retainer holding the rod seal and bushing in place. (5) :- REMOVAL OF ROD SEAL:- To remove rod seal, raise the cylinder head approximately one inch and then lower it back into original position. This will expose the rod Seal for easy removal (BY NO MEANS USE A TOOL TO PRY OR LIFT OUT THE ROD SEAL FROM THE CYLINDER HEAD) (6) :- REMOVAL OF PISTON ROD AND ASSEMBLY:- Remove piston rod and piston assembly from cylinder tubing. (If tubing comes off from cap plate, merely slide piston assembly off from hydraulic cylinders tubing)
(7) :- Remove tie rods from hydraulic cylinder cap.
(8) :- INSPECTION OF INTERNAL PARTS:- Inspect all cylinder parts on internal sue- faces, noting particularly any evidence of foreign matter. (Retain all foreign matte-er for future study, if necessary). Examine parts for evidence of misalignment as evidenced by excessive or uneven wear on parts.
(9) :- CONDITION OF PISTON TUBING, PISTON ROD ETC:- If piston, tubing, piston rod, or piston rod bushing is damaged, the part should be replaced, if available. However, cot erect if necessary, by removing nicks, burrs and other forms of damage. Do not remove more material so as to change the diameters, thus affecting the clearances and fits.
(10) :- REMOVAL OF PISTON ASSEMBLY:- Piston assemblies are staked to prevent the parts from coming loose in operation. If the piston assembly must be taken apart first grind or drill out the stake marks to facilitate dismantling. When removing the upset mate- rial caused due to staking, lightly touch the tool being used to the stake area and remove only the upset material.
To disassemble signal end cylinders you may insert two dowel pins in the spanner pin holes and use a bar to remove the threaded follower, or in the case of double end cylinders remove taper assembly. An alternate method is to clamp the pis- ton assembly by the faces of the followers in a vise and unscrewing.
(NEVER CLAMP THE PISTON ON ITS OUT SIDE DIAMETER).
The vise should be equipped with bronze or brass jaw protectors, if clamping piston rod on chrome plated area.
(11) :- REFITTING OF PISTON ASSEMBLY:- To assemble the piston cup assembly, first as- assemble to the rod, the piston and followers only and tighten the piston assembly tight metal-to-metal. Scribe a diametrical line which is common to both the piston rod and the threaded follower remove the threaded follower and piston, and then place the piston cups into position. While tightening the threaded follower, ensure that it is tightened to the scribe dine on the rod or slightly beyond.
To retake a piston assembly, use a sharp center punch. Stake marks must be in the thread area to be effective. Staking should be accomplished at three points which are different from the original stake marks. When installing the piston assembly into the cylinder tubing, the piston assembly should be inserted into the cylinder tube with the aid of a tapered starting ring or with a piston ring compressor so as not to damage the lip of the cup.
If a tapered ring or compressor is not available, assemble the piston assembly in the tubing as follows Install only the plain follower,one piston cup and the piston on to the rod, and insert that portion of the assembly into the cylinder tube keeping the piston rod as parallel to the center line of the tube as possible. Push the assembly to the opposite end of the tube to within approximately 1/2% ” from the end of the tube , and install the second cup and the threaded follower.
The piston assembly is tightened and staked as indicated above. Assembling the piston assembly in the tube eliminates the problem of starting the lip of the cup into the tubing. Ample lubrication should be done when installing piston into tube. Hydraulic cylinders equipped with followers have small hole drilled through the follower to the base of the cup seal. This hole permits pressure balancing of the cup. Under no circumstances should the hole be closed.
(12) :- INSTALLATION OF TUBING END SEAL (SHEAF SEAL):- Prior to Installing the tube not the hydraulic cylinders cap or head, install tubing end seal.
(13) :- INSTALLATION OF WIPER INTO BUSHING:- In case of single wiper bushings, it is convenient to install the wiper into the bushing before assembly of the bushing on the piston rod. The wiper is not intended as a pressure seal but only as a dirt wiper.
(14) :- REASSEMBLY OF THE CYLINDER:- After the cylinder has been assembled, tighten tie rods snugly with hand wrench and light pressure, and accomplish final tightening grads- ally, working from one tie rod to the diagonally, opposite tie rod to ensure evenness of tightening.
DO NOT TIGHTEN ONE TIE ROD COMPLETELY AND THEN THE OTHERS. THIS WILL RESULT IN IMPROPER ALIGNMENT OF THE HEAD AND CAP.
(15) :- REMOUNTING PROCEDURE:- The ideal method of mounting a hydraulic cylinders to the ma- he cylinder in place ensures perfect align- rod is fays is best to bolt the cylinder down as a last operation of assembly. Alignment can be chine is to have the point of mounting on the equipment machined to the exact dimes sins with proper alignment, so that bolting t meant. In many cases, this is not practical from a cost and design stand point. Therefore alignment must be secured at the time of installation.
Whenever the piston tensed to the machine, which confines the cylinder in one position, it is found that it free secured in other ways, but the following sequence of installation is quite effective.
A:- Assemble the piston rod to the machine. The piston rod must be fastened and held rely, so its center line is parallel to the guides (or parallel to the line of movement in case of fixed mounted cylinders).
B :- Insert mounting bolts but do B. Insert mounting bolts but do not tighten them.
C :- In the case horizontally mounted cylinders, its necessary to support the weightlifter cylinder body so as to eliminate strain on the piston rod.
D :- Use feeler gauges under the mounting and insert shims at these points equal to the thickness indicated by the feeler gauges.
E :- Finally, tighten the mounting bolts.
F :- lf possible, the machine operation should be tested with low pressure air lo ensure that Hydraulic Cylinders and attached parts are operating freely. This should be done without machine operating under load conditions.
NOTE :-A little extra care in aligning the cylinder properly will pay dividends in terms of long, trouble-free service, and is well worth the additional time and efforts.
Whenever possible, damaged parts, especially seals, should be sent to Inductotherm along with a complete report to pass on the data to manufacturer for through analysis. It will help to overcome service difficulties encountered as a result of adverse operating conditions or improper application.